/*****************************************************************************

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Copyright (c) 2014, 2018, MariaDB Corporation.

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*****************************************************************************/

/**************************************************//**
@file include/buf0flu.h
The database buffer pool flush algorithm

Created 11/5/1995 Heikki Tuuri
*******************************************************/

#ifndef buf0flu_h
#define buf0flu_h

#include "ut0byte.h"
#include "log0log.h"
#include "buf0types.h"

/** Flag indicating if the page_cleaner is in active state. */
extern bool buf_page_cleaner_is_active;

#ifdef UNIV_DEBUG

/** Value of MySQL global variable used to disable page cleaner. */
extern my_bool		innodb_page_cleaner_disabled_debug;

#endif /* UNIV_DEBUG */

/** Event to synchronise with the flushing. */
extern os_event_t	buf_flush_event;

class ut_stage_alter_t;

/** Handled page counters for a single flush */
struct flush_counters_t {
	ulint	flushed;	/*!< number of dirty pages flushed */
	ulint	evicted;	/*!< number of clean pages evicted */
	ulint	unzip_LRU_evicted;/*!< number of uncompressed page images
				evicted */
};

/********************************************************************//**
Remove a block from the flush list of modified blocks. */
void
buf_flush_remove(
/*=============*/
	buf_page_t*	bpage);	/*!< in: pointer to the block in question */
/*******************************************************************//**
Relocates a buffer control block on the flush_list.
Note that it is assumed that the contents of bpage has already been
copied to dpage. */
void
buf_flush_relocate_on_flush_list(
/*=============================*/
	buf_page_t*	bpage,	/*!< in/out: control block being moved */
	buf_page_t*	dpage);	/*!< in/out: destination block */
/** Update the flush system data structures when a write is completed.
@param[in,out]	bpage	flushed page
@param[in]	dblwr	whether the doublewrite buffer was used */
void buf_flush_write_complete(buf_page_t* bpage, bool dblwr);

/** Assign the full crc32 checksum for non-compressed page.
@param[in,out]	page	page to be updated */
void buf_flush_assign_full_crc32_checksum(byte* page);

/** Initialize a page for writing to the tablespace.
@param[in]	block			buffer block; NULL if bypassing the buffer pool
@param[in,out]	page			page frame
@param[in,out]	page_zip_		compressed page, or NULL if uncompressed
@param[in]	newest_lsn		newest modification LSN to the page
@param[in]	use_full_checksum	whether tablespace uses full checksum */
void
buf_flush_init_for_writing(
	const buf_block_t*	block,
	byte*			page,
	void*			page_zip_,
	lsn_t			newest_lsn,
	bool			use_full_checksum);

# if defined UNIV_DEBUG || defined UNIV_IBUF_DEBUG
/********************************************************************//**
Writes a flushable page asynchronously from the buffer pool to a file.
NOTE: buf_pool->mutex and block->mutex must be held upon entering this
function, and they will be released by this function after flushing.
This is loosely based on buf_flush_batch() and buf_flush_page().
@return TRUE if the page was flushed and the mutexes released */
ibool
buf_flush_page_try(
/*===============*/
	buf_pool_t*	buf_pool,	/*!< in/out: buffer pool instance */
	buf_block_t*	block)		/*!< in/out: buffer control block */
	MY_ATTRIBUTE((warn_unused_result));
# endif /* UNIV_DEBUG || UNIV_IBUF_DEBUG */
/** Do flushing batch of a given type.
NOTE: The calling thread is not allowed to own any latches on pages!
@param[in,out]	buf_pool	buffer pool instance
@param[in]	type		flush type
@param[in]	min_n		wished minimum mumber of blocks flushed
(it is not guaranteed that the actual number is that big, though)
@param[in]	lsn_limit	in the case BUF_FLUSH_LIST all blocks whose
oldest_modification is smaller than this should be flushed (if their number
does not exceed min_n), otherwise ignored
@param[out]	n		the number of pages which were processed is
passed back to caller. Ignored if NULL
@retval true	if a batch was queued successfully.
@retval false	if another batch of same type was already running. */
bool
buf_flush_do_batch(
	buf_pool_t*		buf_pool,
	buf_flush_t		type,
	ulint			min_n,
	lsn_t			lsn_limit,
	flush_counters_t*	n);

/** This utility flushes dirty blocks from the end of the flush list of all
buffer pool instances.
NOTE: The calling thread is not allowed to own any latches on pages!
@param[in]	min_n		wished minimum mumber of blocks flushed (it is
not guaranteed that the actual number is that big, though)
@param[in]	lsn_limit	in the case BUF_FLUSH_LIST all blocks whose
oldest_modification is smaller than this should be flushed (if their number
does not exceed min_n), otherwise ignored
@param[out]	n_processed	the number of pages which were processed is
passed back to caller. Ignored if NULL.
@return true if a batch was queued successfully for each buffer pool
instance. false if another batch of same type was already running in
at least one of the buffer pool instance */
bool
buf_flush_lists(
	ulint			min_n,
	lsn_t			lsn_limit,
	ulint*			n_processed);

/******************************************************************//**
This function picks up a single page from the tail of the LRU
list, flushes it (if it is dirty), removes it from page_hash and LRU
list and puts it on the free list. It is called from user threads when
they are unable to find a replaceable page at the tail of the LRU
list i.e.: when the background LRU flushing in the page_cleaner thread
is not fast enough to keep pace with the workload.
@return true if success. */
bool
buf_flush_single_page_from_LRU(
/*===========================*/
	buf_pool_t*	buf_pool);	/*!< in/out: buffer pool instance */
/******************************************************************//**
Waits until a flush batch of the given type ends */
void
buf_flush_wait_batch_end(
/*=====================*/
	buf_pool_t*	buf_pool,	/*!< in: buffer pool instance */
	buf_flush_t	type);		/*!< in: BUF_FLUSH_LRU
					or BUF_FLUSH_LIST */
/**
Waits until a flush batch of the given lsn ends
@param[in]	new_oldest	target oldest_modified_lsn to wait for */

void
buf_flush_wait_flushed(
	lsn_t		new_oldest);

/********************************************************************//**
This function should be called at a mini-transaction commit, if a page was
modified in it. Puts the block to the list of modified blocks, if it not
already in it. */
UNIV_INLINE
void
buf_flush_note_modification(
/*========================*/
	buf_block_t*	block,		/*!< in: block which is modified */
	lsn_t		start_lsn,	/*!< in: start lsn of the first mtr in a
					set of mtr's */
	lsn_t		end_lsn,	/*!< in: end lsn of the last mtr in the
					set of mtr's */
	FlushObserver*	observer);	/*!< in: flush observer */
/********************************************************************//**
Returns TRUE if the file page block is immediately suitable for replacement,
i.e., transition FILE_PAGE => NOT_USED allowed.
@return TRUE if can replace immediately */
ibool
buf_flush_ready_for_replace(
/*========================*/
	buf_page_t*	bpage);	/*!< in: buffer control block, must be
				buf_page_in_file(bpage) and in the LRU list */

#ifdef UNIV_DEBUG
/** Disables page cleaner threads (coordinator and workers).
It's used by: SET GLOBAL innodb_page_cleaner_disabled_debug = 1 (0).
@param[in]	save		immediate result from check function */
void buf_flush_page_cleaner_disabled_debug_update(THD*,
						  st_mysql_sys_var*, void*,
						  const void* save);
#endif /* UNIV_DEBUG */

/******************************************************************//**
page_cleaner thread tasked with flushing dirty pages from the buffer
pools. As of now we'll have only one coordinator of this thread.
@return a dummy parameter */
extern "C"
os_thread_ret_t
DECLARE_THREAD(buf_flush_page_cleaner_coordinator)(
/*===============================================*/
	void*	arg);		/*!< in: a dummy parameter required by
				os_thread_create */

/** Adjust thread count for page cleaner workers.
@param[in]	new_cnt		Number of threads to be used */
void
buf_flush_set_page_cleaner_thread_cnt(ulong new_cnt);

/******************************************************************//**
Worker thread of page_cleaner.
@return a dummy parameter */
extern "C"
os_thread_ret_t
DECLARE_THREAD(buf_flush_page_cleaner_worker)(
/*==========================================*/
	void*	arg);		/*!< in: a dummy parameter required by
				os_thread_create */
/** Initialize page_cleaner. */
void
buf_flush_page_cleaner_init(void);

/** Wait for any possible LRU flushes that are in progress to end. */
void
buf_flush_wait_LRU_batch_end(void);

#if defined UNIV_DEBUG || defined UNIV_BUF_DEBUG
/******************************************************************//**
Validates the flush list.
@return TRUE if ok */
ibool
buf_flush_validate(
/*===============*/
	buf_pool_t*	buf_pool);
#endif /* UNIV_DEBUG || UNIV_BUF_DEBUG */

/********************************************************************//**
Initialize the red-black tree to speed up insertions into the flush_list
during recovery process. Should be called at the start of recovery
process before any page has been read/written. */
void
buf_flush_init_flush_rbt(void);
/*==========================*/

/********************************************************************//**
Frees up the red-black tree. */
void
buf_flush_free_flush_rbt(void);
/*==========================*/

/********************************************************************//**
Writes a flushable page asynchronously from the buffer pool to a file.
NOTE: in simulated aio we must call
os_aio_simulated_wake_handler_threads after we have posted a batch of
writes! NOTE: buf_pool->mutex and buf_page_get_mutex(bpage) must be
held upon entering this function, and they will be released by this
function.
@return TRUE if page was flushed */
ibool
buf_flush_page(
/*===========*/
	buf_pool_t*	buf_pool,	/*!< in: buffer pool instance */
	buf_page_t*	bpage,		/*!< in: buffer control block */
	buf_flush_t	flush_type,	/*!< in: type of flush */
	bool		sync);		/*!< in: true if sync IO request */
/********************************************************************//**
Returns true if the block is modified and ready for flushing.
@return true if can flush immediately */
bool
buf_flush_ready_for_flush(
/*======================*/
	buf_page_t*	bpage,	/*!< in: buffer control block, must be
				buf_page_in_file(bpage) */
	buf_flush_t	flush_type)/*!< in: type of flush */
	MY_ATTRIBUTE((warn_unused_result));

/******************************************************************//**
Check if there are any dirty pages that belong to a space id in the flush
list in a particular buffer pool.
@return number of dirty pages present in a single buffer pool */
ulint
buf_pool_get_dirty_pages_count(
/*===========================*/
	buf_pool_t*	buf_pool,	/*!< in: buffer pool */
	ulint		id,		/*!< in: space id to check */
	FlushObserver*	observer);	/*!< in: flush observer to check */

/*******************************************************************//**
Synchronously flush dirty blocks from the end of the flush list of all buffer
pool instances.
NOTE: The calling thread is not allowed to own any latches on pages! */
void
buf_flush_sync_all_buf_pools(void);
/*==============================*/

/** Request IO burst and wake page_cleaner up.
@param[in]	lsn_limit	upper limit of LSN to be flushed */
void
buf_flush_request_force(
	lsn_t	lsn_limit);

/** We use FlushObserver to track flushing of non-redo logged pages in bulk
create index(BtrBulk.cc).Since we disable redo logging during a index build,
we need to make sure that all dirty pages modifed by the index build are
flushed to disk before any redo logged operations go to the index. */

class FlushObserver {
public:
	/** Constructor
	@param[in,out]	space		tablespace
	@param[in]	trx		trx instance
	@param[in]	stage		performance schema accounting object,
	used by ALTER TABLE. It is passed to log_preflush_pool_modified_pages()
	for accounting. */
	FlushObserver(fil_space_t* space, trx_t* trx, ut_stage_alter_t* stage);

	/** Deconstructor */
	~FlushObserver();

	/** Check pages have been flushed and removed from the flush list
	in a buffer pool instance.
	@param[in]	instance_no	buffer pool instance no
	@return true if the pages were removed from the flush list */
	bool is_complete(ulint	instance_no)
	{
		return(m_flushed->at(instance_no) == m_removed->at(instance_no)
		       || m_interrupted);
	}

	/** @return whether to flush only some pages of the tablespace */
	bool is_partial_flush() const { return m_stage != NULL; }

	/** @return whether the operation was interrupted */
	bool is_interrupted() const { return m_interrupted; }

	/** Interrupt observer not to wait. */
	void interrupted()
	{
		m_interrupted = true;
	}

	/** Check whether the operation has been interrupted */
	void check_interrupted();

	/** Flush dirty pages. */
	void flush();
	/** Notify observer of flushing a page
	@param[in]	buf_pool	buffer pool instance
	@param[in]	bpage		buffer page to flush */
	void notify_flush(
		buf_pool_t*	buf_pool,
		buf_page_t*	bpage);

	/** Notify observer of removing a page from flush list
	@param[in]	buf_pool	buffer pool instance
	@param[in]	bpage		buffer page flushed */
	void notify_remove(
		buf_pool_t*	buf_pool,
		buf_page_t*	bpage);
private:
	/** Tablespace */
	fil_space_t*		m_space;

	/** Trx instance */
	const trx_t* const	m_trx;

	/** Performance schema accounting object, used by ALTER TABLE.
	If not NULL, then stage->begin_phase_flush() will be called initially,
	specifying the number of pages to be attempted to be flushed and
	subsequently, stage->inc() will be called for each page we attempt to
	flush. */
	ut_stage_alter_t*	m_stage;

	/* Flush request sent */
	std::vector<ulint>*	m_flushed;

	/* Flush request finished */
	std::vector<ulint>*	m_removed;

	/* True if the operation was interrupted. */
	bool			m_interrupted;
};

#include "buf0flu.ic"

#endif
